The long range goal of this project is to use electron microscopy and freeze fracture techniques to study the structure of myelin and cell membranes in CNS tissue and in subcellular fractions. Current projects are concerned with the biochemical characterization of myelin isolated from Xenopus frogs and tadpoles, the developmental origin of proteins and glycoproteins in myelin sheaths of the rabbit optic nerve and the electron microscopic appearance in freeze fracture replicas of myelin and axolemma enriched membranes isolated from rabbit optic nerves.